What is the test for establishing a trial when the trial has been deemed started?

^3. For purposes of section 1382, providing a statutory speedy trial right, trial begins when elements "vital to undertaking a trial be present" and the parties are "'ready to proceed[.]'" (People v. Hajjaj (2010) 50 Cal.4th 1184, 1196-1197; see Perryman v. Superior Court (2006) 141 Cal.App.4th 767, 776 (Perryman) [trial begins "when jeopardy attaches . . . or when the litigation of contested issues otherwise begins"].) Had the trial not been deemed started at that time, the People would have had to show good cause for a continuance to secure their witnesses. (Perryman, supra, 141 Cal.App.4th at pp. 777-778.)